On Thu 09-04-20 23:38:13, Guoqing Jiang wrote:
[...]
> Not know memalloc_noio_{save,restore} well, but I guess it is better
> to use them to mark a small scope, just my two cents.
This would go against the intentio of the api. It is really meant to
define reclaim recursion problematic scope. If there is a clear entry
point where any further allocation recursing to FS/IO could deadlock
then it should be used at that level. This might be a lock which is
taken from the reclaim or like this case a device is suspended and no IO
is processed so anything that would wait for an IO or rely on IO making
progress in the reclaim path would deadlock.
Please have a look at Documentation/core-api/gfp_mask-from-fs-io.rst
and let me know is something could be made more clear or explicit.
I am more than happy to improve the documentation.
--
Michal Hocko
SUSE Labs
